The first instructional lesson in all my Government classes, AP and regular, has students answering a warm-up:  "What is Justice?  Write down your answer."  I step outside the room ostensibly to run an errand, then put on a black robe, a peruke, throw open the door, and the fun begins.  
Usually the first response from the mainly 10th graders in the room is that justice is punishing those who break the law?  I will then challenge - if the student is African-America I might ask "does that mean that Harriet Tubman should have gone to prison, perhaps for the rest of her life, for the many slaves she smuggled out of Dorchester County?"  If Jewish I might respond with remarks about Mies Giep and her family hiding the family of Otto Frank in Amsterdam, including his daughter Anne - should they have been executed by the Nazis?  Whatever the student says, I push further.
We explore the idea that the question "what is justice" goes back at least to Plato's Republic, and note references to justice in the Declaration (for example, "He has obstructed the Administration of Justice, by refusing his Assent to Laws for establishing Judiciary powers") and the Preamble ("establish Justice").  We then go on to the idea of the social contract, where Hobbes say the life of man in a state of nature without a social contract is "solitary, poor, nasty, brutish and short" and Locke argues that we establish a social contract surrendering some of our rights in order that the others be protected, a notion clearly in the Declaration